A typical data storage system includes a rigid housing having a base and a cover that encloses a variety of components. The components include one or more discs having data surfaces that are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor that causes the discs to spin and the data surfaces of the discs to pass under respective aerodynamic bearing disc head sliders. The sliders carry magnetic transducers, which write information to and read information from the data surfaces of the discs. Typically, magnetic transducers or magnetic heads include an inductive recording or write head for generating a magnetic field that aligns the magnetic moments of the recording layer of a magnetic medium to represent desired bits of data. In addition, transducers include a read element that is configured to read magnetic flux transitions recorded to data tracks on the medium which represent the bits of data.
The components also include an actuator mechanism that moves the sliders across the data surfaces of the discs. The actuator mechanism includes a motor, such as a voice coil motor (VCM), a track accessing arm and suspensions that support the sliders. The voice coil motor is operated so as to move the actuator mechanism about an actuator pivot center such that the sliders move from track-to-track across the data surface of a disc.
Magnetic recording heads include either longitudinal or perpendicular recording techniques. Perpendicular recording is a form of magnetic recording in which magnetic moments representing bits of data are oriented perpendicularly to the surface of the recording layer of the recording medium, as opposed to longitudinally along a track of the medium as in the more traditional longitudinal recording technique. Currently, there is an increased use of perpendicular recording techniques because of its ability to put more bits of data per square inch of disc space (i.e. areal density) as well as its ability to retain its magnetic charge (i.e. coercivity). However, the influence of external stray fields that originate external to the data storage system and internal stray fields that originate internal to the data storage system can detrimentally effect perpendicular recording compared to traditional longitudinal recording. In some conditions, stray fields can generate a localized magnetic field at the magnetic recording head and cause a variety of reliability issues on the perpendicular recording process. Examples include destabilization of magnetized media, reorientation of recorded magnetized media and, in some circumstances, the generation of media magnetization reversal in non-operation modes if the stray field becomes concentrated and amplified.
Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.